Understanding Protein Folding with GRP78

Mon, 11/25/2013 - 15:30

HSP70 family member GRP78 (78 kD glucose-regulated protein) is an abundant protein cofactor commonly known as a molecular chaperone. Found in most eukaryotes, Hsp genes are members of a heat-inducible multigene family. These proteins are found in most cellular compartments of eukaryotes - everything from nuclei, mitochondria, chloroplasts, to endoplasmic reticulum (ER) and cytosol. Its main role is thought to be in the ER where it controls the maturation of glycoproteins and protein folding, but it also functions as a ligand receptor and is expressed on the cell surface, as reviewed by Gonzalez-Gronow (1). There, its association with a variety of proteins such as the voltage-dependent anion channel (VDAC), major histocompatibility complex class I (MHC-I), and the Dna-like protein MTJ-1 may be due to an unusual, compartmentalized surface topography. As a potential targeted therapy receptor in oncology and chronic vascular disease, GRP78 indicates poor prognosis when found in patient sera (2). GRP78 activates the downstream pathways of Akt, NFk B, and oncogenic Cripto to promote cell proliferation and endothelial cell survival.

Immunocytochemistry/Immunofluorescence: GRP78 Antibody Immunocytochemistry/Immunofluorescence: GRP78 Antibody

Conversely, its association with the plasminogen kringle 5 domain or Par-4 produces apoptosis (3). This orchestration of diverse functions appears to be directed by GRP’s compartmentalized features and indeed several GRP78 targeting peptides with honed tumor specificity have been found from different tumors. The GRP78 antibody has also been used to show that the pro-oxidant enzyme NADPH oxidase (NOX2) is a significant contributor to the deleterious effects of a high-fat diet, indicating that the NOX pathway may be a potential target for metabolic therapies (4).

  1. PMID: 19331544
  2. PMID: 20807604
  3. PMID: 20807604
  4. PMID: 23233541

Novus Biologicals offers GRP78 reagents for your research needs including:

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